UNIV.  OF  FL  LIB. 
DOCUf 


MENTS  DEFT. 


A.  I.  32. 


1 


U.S.  DEPOSITORY 


c_ 


Issued  May  20,  1918. 


United  States  Department  of  Agriculture^'-*!^ 

BUREAU  OF  ANIMAL  INDUSTRY.  JT^O  ••**"*  *#*v5f     - 


JOHN  R.  MOHLER,   Chief  of  Bureau. 


OAK  POISONING  OF  LIVE  STOCK. 


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By  C.  Dwight  Marsh,  Physiologist  in  Charge  of  Poisowous  JUaAlTmestigation^' 
A.  B.   Clawson,  Physiologist,  and  Hadleigh  Maesh,  yeflgfc^tSli*- Tft****^-^ 


Pathological  Division. 


*"*„*!*'* 


PREVALENCE. 


For  some  years  there  have  been  reports  of  poisoning  of  live  stock 
b}  oak  leaves  on  the  western  stock  ranges.  These  reports  have  come 
mostly  from  Colorado,  Utah,  Texas,  and  New  Mexico. 

In  the  mountains  of  Utah  there  is  a  very  distinct  oak  zone  between 
the  altitudes  of  5,500  and  8,000  feet,  in  which  the  species  known  as 
Quercus  gambellii  is  the  principal  form  of  vegetation.  When  the 
cattle  go  to  the  summer  range  they  graze  through  this  zone  at  the 
time  when  the  young  leaves  of  the  oak  are  appearing,  and  again  late 
in  summer  they  frequently  come  down  from  the  higher  ranges  and 
stay  in  the  oak  zone,  eating  largely  of  the  leaves.  It  is  generally 
said  that  most  of  the  cases  of  so-called  oak  poisoning  occur  in  the 
spring,  when  the  animals  are  eating  the  buds  and  young  leaves. 

In  Texas  and  New  Mexico  cattle  are  said  to  be  poisoned  by  the 
"  shinnery  "  oak,  Quercus  havardi,  in  the  early  spring.  In  the  Texas 
shinnery  country  the  cattle  are  kept  in  pastures  where  the  vegetation 
consists  mainly  of  shinnery,  mesquite,  bear  grass  (Nolina),  sage, 
grama  grass,  and  a  few  weeds.  Of  these  plants  the  shinnery  is  the 
first  to  begin  growing  early  in  the  spring. 

Reports  from  stockmen  in  regard  to  oak  poisoning  have  been  some- 
what contradictory,  and  the  matter  has  been  made  a  subject  of  special 
investigation  for  the  last  three  years  with  the  field  experimental 
work  in  Utah  and  Texas.  The  subject  has  proved  to  be  one  of  con- 
siderable difficulty,  requiring  many  experimental  feedings.  While 
there  are  still  some  doubtful  points,  it  is  considered  that  the  work  is 
now  fairly  complete  from  the  practical  side,  and  a  technical  report 
is  in  preparation.  Inasmuch  as  it  may  be  some  time  before  this 
technical  report  appears,  and  as  it  is  important  that  stockmen  should 
have  all  available  information  as  soon  as  possible  in  order  to  reduce 
their  losses,  it  has  seemed  wise  to  issue  a  concise  preliminary  paper 
giving  the  main  results  of  the  investigation. 

55952°— 18 


ANIMALS  POISONED. 

The  losses  from  oak  in  America  seem  to  be  confined  to  cattle, 
although  there  have  been  unconfirmed  reports  of  the  poisoning  of 
sheep.     No  cases  of  the  poisoning  of  horses  are  known. 

. 
OAK  THE  CAUSE  OF  THE  TROUBLE. 

It  has  been  definitely  proved  that  the  cause  of  this  illness  is  the 
oak.  This  has  been  shown  experimentally  in  Utah  and  Texas,  and 
doubtless  would  be  equally  true  for  other  localities. 

In  Utah  the  usual  time  for  the  cases  to  occur  is  in  the  spring  when 
the  cattle  are  driven  to  the  summer  range.  They  frequently  pass  into 
the  oak  zone  so  early  that  the  grass  has  not  started,  so  that  there  is 
little  for  them  to  eat  except  the  oak.  Many  of  the  animals  have  come 
from  dry  feed,  are  greedy  for  green  material,  and  naturally  eat 
largely  of  the  young  oak  leaves.  Similar  conditions  obtain  in  Texas. 
At  the  time  when  the  shinnery  oak  begins  to  put  out  leaves  there  is 
practically  nothing  else  on  the  range  for  the  cattle  to  eat,  and  by 
necessity  they  devote  themselves  to  it.  It  has  been  shown  by  observa- 
tion that  they  do  not  eat  shinnery  by  preference,  but  will  take  grass 
more  readily  if  any  is  to  be  found. 

OAK  NOT  NECESSARILY  INJURIOUS. 

While  it  has  been  shown  that  illness  may  result  from  eating  oak 
brush,  it  does  not  follow  in  all  cases.  The  number  of  cases  of  sick- 
ness is  comparatively  small,  although  in  some  localities  in  the  early 
spring  oak  leaves  are  about  all  that  the  animal  can  get  to  eat.  In 
the  shinnery  country  the  annual  loss  is  estimated  at  3  per  cent,  which 
indicates  that  comparatively  few  of  the  cattle  suffer  from  their  oak 
diet.  If  the  animals  feed  exclusively  or  nearly  exclusively  on  oak, 
some  of  them  may  be  affected,  but  many  will  go  through  the  season 
with  no  serious  harm.  It  has  been  found  experimentally  that  if  a 
small  quantity  of  hay  is  added  to  the  daily  ration,  no  harm  results 
from  the  oak  feeding.  With  a  certain  quantity  of  other  material 
oak  may  be  considered  as  good  forage.  As  a  matter  of  fact,  cattle  in 
Utah  frequently  come  off  the  oak  ranges  in  the  fall  in  fine  condition. 

SYMPTOMS. 

Perhaps  the  most  noticeable  symptom  is  the  extreme  constipation. 
The  feces  are  passed  infrequently,  are  dark  and  hard,  consisting  at 
times  largely  of  mucus,  and  sometimes  are  bloody.  This  condition 
of  constipation  may  be  followed  by  diarrhea. 

The  animal  becomes  gaunt,  its  coat  rough,  its  nose  dry  and  cracked. 
The  attitude  is  peculiar,  the  head  being  extended  forward.     Appetite 


is  lost  and  weakness  increases  until  the  case  is  ended  by  death.  The 
temperature  and  respiration  are  normal. 

These  symptoms  appear  after  rather  prolonged  feeding  upon  the 
oak,  not  less  than  about  a  week.  The  animals  may  die  in  two  weeks 
or  they  may  linger  for  an  indefinite  period. 

In  the  autopsies  the  congested  condition  of  the  interior  of  the 
intestine  and  sometimes  of  the  fourth  stomach  is  most  noticeable. 

TREATMENT  OF  OAK  CASES. 

From  the  fact  that  oak  cases  are  constipated,  it  is  evident  that  any 
treatment  relieving  this  condition  would  be  helpful.  Epsom  salt 
might  be  used  in  pound  doses,  or  it  could  be  given  in  the  water,  in 
small  quantities,  in  localities  where  the  cattle  are  watered  at  wells. 

It  is  evident,  however,  from  what  has  been  said,  that  the  sensible 
thing  is  to  prevent  trouble  by  proper  feeding.  If  cattle  are  turned 
upon  an  oak  range  when  there  is  little  other  vegetation,  some  loss 
must  be  expected.  There  is  no  doubt  that  in  some  localities  cattle 
are  admitted  to  the  summer  range  too  early.  In  such  cases  it  would 
be  more  profitable,  in  the  end,  to  feed  a  little  longer  and  use  the 
range  only  after  the  grasses  have  had  a  fair  start.  The  exact  time 
when  this  should  be  done  can  not  be  determined  in  advance  but  should 
be  fixed  each  year  after  an  actual  examination  of  the  range. 

If  cattle  are  confined  in  pastures  containing  oak,  care  should  be 
taken  that  the  diet  is  not  exclusively  oak.  It  has  been  found  that  as 
small  a  quantity  as  3  pounds  of  alfalfa  hay  daily,  with  the  oak,  will 
provide  a  maintenance  ration  for  a  2-year-old  steer. 


WASHINGTON  :  GOVERNMENT  PBINTINC.  OFFICE  I  1918 


UNIVERSITY  OF  FLORIDA 


3  1262  08925  9583 


